Effect of recovery heat treatment on microstructure and mechanical properties of R26 superalloy bolts

doi:10.13251/j.issn.0254-6051.2023.05.028

Abstract

Abstract: Recovery heat treatment was carried out for the R26 superalloy bolts which had serviced about 60 000 hours in a power station. The effect of recovery heat treatment on microstructure and mechanical properties of the R26 superalloy bolts was investigated by means of chemical composition analysis, metallographic microstructure observation, mechanical property test and fracture analysis. The results show that the microstructure of the R26 alloy is mainly austenite with a large number of twin crystals. There are discontinuous precipitated carbides along the grain boundaries of the R26 superalloy with abnormal hardness. After recovery heat treatment, the grain is refined and homogenized, and the carbides which locate on the grain boundary are dissolved, moreover, the γ′ phases are precipitated in the grain. The recovery heat treatment can restore the hardness value of the R26 alloy bolts to the standard range, and improve the plasticity and toughness.

Key words: nickel-based superalloy, R26 alloy bolts, recovery heat treatment, microstructure, mechanical properties

CLC Number:

TG132.3

Han Zhewen, Wang Zhichun, Wang Jiajian, Wang Qibing, Peng Bo, Zuo Yue, Si Mingyu, Kang Ju. Effect of recovery heat treatment on microstructure and mechanical properties of R26 superalloy bolts[J]. Heat Treatment of Metals, 2023, 48(5): 184-190.

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